Prostate Cancer In Dogs - Causes, Symptoms & Treatment

Prostate tumors are uncommon in dogs but are usually very malignant and aggressive. The most common is adenocarcinoma. It occurs in only 0.3-0.6 % of dogs, most often in dogs older than 10 years old.

What is prostate gland?

The prostate gland is a male accessory gonad. Its function is the secretion of seminal plasma, which contains many proteins. The prostate is a semioval bilobular exocrine gland. Dorsally it is in contact with the rectum, ventrally with the pubic symphysis, laterally with the abdominal wall, and cranially with the bladder.

The prostate is covered with a fibromuscular tissue capsule. It is palpatory rectally. It has two lobes. The gland communicates with the urethra. It is mostly composed of secretory glandular tissue, and histologically it is not differentiated into areas.

Prostatic secretion depends on testosterone which is produced in the testicles. Neutered dogs lack testosterone which leads the prostate to atrophy.

What is prostate cancer in dogs?

Prostate cancer in dogs often arises from epithelial cells. There are two types of prostate cancer in dogs:

adenocarcinoma
transitional cell carcinoma.

That malignant tumor develops in both neutered and intact male dogs. It represents <1% of all canine malignancies but is the most common prostatic disorder in neutered male dogs. Metastasis to regional lymph nodes, lungs, and the lumbosacral skeleton is common.

Also, cancer can spread from elsewhere in the body and usually are associated with the immune system; it usually occurs in medium to large-breed male dogs, both intact or neutered. The median age is 9-10 years old.

Benign or noncancerous tumors are rare, and the most common is leiomyoma. Other prostate gland disorders include benign prostatic hyperplasia, prostatitis, cysts, abscess, and prostatomegaly.

cavalier dog

Causes of prostate cancer in dogs

The reason why pets may develop any type of cancer is not straightforward. Usually, it takes more than one cause; uncontrolled growth of cells is caused by a complex mix of factors like genetics or hereditary.

The tumor can arise from both glandular or ductal epithelial cells of the prostate or the urothelium of the prostatic urethra. Still, in most cases, the precise cellular origin remains unknown. The other common prostatic neoplasm in dogs is transitional cell carcinoma derived from the prostatic urethra.

Other tumors such as sarcomatoid carcinoma, primary and metastatic hemangiosarcoma, and lymphoma have been reported rarely. The potential link between early neutering and the increased risk of developing prostatic adenocarcinoma has been found.

Benign growth of the prostate is commonly seen in older unfixed dogs and is caused by the hormones testosterone and estrogens. In the case of prostate cancer, there is no specific factor, but some breeds seem to be at increased risk, such as

Doberman Pinscher
Scottish Terrier
Beagle
Miniature Poodle.

Symptoms of prostate cancer

Sometimes symptoms are less obvious, such as lethargy, weight loss, lack of appetite, etc. The most common symptoms you may see are related to the urinary tract.

The most common is blood in urine because enlargened prostate compresses the urethra, leading to unusual urinary habits. But if you notice some of the mentioned symptoms, you should take your dog to the vet.

Difficulty and frequent attempts at urinating
Haematuria
Tenesmus usually with the production of ribbon-like stool
Watery or bloody discharge from the penis
Holding the tail in unusual positions
Scooting the anus
Weight loss
Stranguria and dysuria
Rear limb lameness
Weakness
Lethargy
Exercise intolerance
Fatigue
Fever

However, symptoms may not be limited to the urinary tract as cancer spreads and affect other organs. This type of cancer usually spreads to nearby organs, lungs (coughing, heavily breathing), bones (limp of limbs), brain, and spinal cord (neurological dysfunction).

pug looking

Diagnosis

Diagnosis of prostatic cancer in dogs usually is based on history, clinical signs, prostatic imaging, fluid analysis, cytology, and histopathology.

Screening tests include

clinical examination
blood tests
urinalysis

Some physical examination findings include firm, asymmetrical, immobile prostate gland, prostatomegaly, pain, and sometimes the vet may note caudal abdominal mass, cachexia, pyrexia, and dyspnea.

Other diagnosing methods include abdominal ultrasound, CT scan, X-rays, and possibly biopsy, aspiration, and cytology.

Radiographic changes can include prostatomegaly, mineralization of the prostate, evidence of regional lymphadenomegaly, and possibly evidence of metastasis to the lungs and bones, especially to the lumbar vertebrae and pelvis. Ultrasound findings include focal to diffuse hyperechoic areas, mineralization, and loss of normal prostatic contour.

Treatment

Since canine prostate cancer is aggressive and highly metastatic, ideally, both local and systemic therapies are indicated. However, there is currently no widely accepted standard of care, and treatment options are limited and rather unrewarding.

NSAIDs, such as piroxicam, can be given in combination with chemotherapeutic cisplatin. Radiation therapy did not improve survival significantly, and its role in the treatment of canine prostatic neoplasia is unclear.

Other treatment options include palliative partial or total surgical prostatectomy.

Progression and prognosis

In general, the survival for most dogs with clinical prostate cancer is short, often only ranging from weeks to months. Cancer can be one-sided or both-sided.

Since prostate cancer in dogs is very aggressive, it can spread to other nearby tissues, such as the bladder but not to regional lymph nodes. In the next stage, it spreads to regional lymph nodes and metastases to other body parts.

dog sleeping

Prevention of prostate cancer

Neutering does not seem to prevent or initiate tumor development, but it favors tumor progression. This may result from luteinizing hormone (LH) concentrations that persist for the dog's life following neutering due to the loss of negative testicular feedback. LH receptors are present within human prostatic epithelium but have not yet been investigated in dog normal or neoplastic prostate tissue.

Testosterone stimulation in dogs is not related to the development of prostate cancer. Accordingly, neutering is not protective against canine prostate cancer.

Conclusion

Prostate is male secretory gonad. Malignant tumors can develop in neutered and intact dogs, and it is usually adenocarcinoma. The cause of developing tumors is a mix of risk factors, including genetics.

In the first stage, symptoms are less obvious; later, they are usually from urogenital systems, such as haematuria or paraneoplastic syndrome if metastasized. Diagnosis is based on history, clinical examination, rectal examination, blood tests and urinalysis, ultrasound, x-rays, CT scan, and pathohistological findings. It can be treated with a combination of NSAIDs, chemotherapeutic drugs, radiation, or surgically if it is localized.

It is highly metastatic, so the prognosis is not very well and usually includes only palliative treatment. Neutering does not seem to prevent or initiate tumor development. Still, some studies have shown a potential link between neutering too early and the increased risk of developing prostatic adenocarcinoma.

World Dog Finder team

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